Note 7 - Loans (Details) - Aging of Loan Portfolio (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 7,832,013	$ 7,429,147
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	17,034	16,832
60-89 Days Past Due	4,136	1,610
Greater than 90 Days Past Due		630
Non-accrual Loans	24,506	19,958
Total Past Due	45,676	39,030
Loans Not Past Due	2,192,226	2,088,077
Total	2,237,902	2,127,107
Real Estate Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	0	0
60-89 Days Past Due	0	1,471
Greater than 90 Days Past Due	0	0
Non-accrual Loans	28,995	36,299
Total Past Due	28,995	37,770
Loans Not Past Due	160,872	143,180
Total	189,867	180,950
Commercial Mortgage Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	2,396	21,570
60-89 Days Past Due	262	3,627
Greater than 90 Days Past Due	499	0
Non-accrual Loans	35,996	35,704
Total Past Due	39,153	60,901
Loans Not Past Due	3,882,195	3,707,551
Total	3,921,348	3,768,452
Residential Mortgage And Equity Lines Member
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	3,310	5,324
60-89 Days Past Due	2,237	1,972
Greater than 90 Days Past Due	0	0
Non-accrual Loans	10,364	11,941
Total Past Due	15,911	19,237
Loans Not Past Due	1,451,736	1,320,845
Total	1,467,647	1,340,082
Installment And Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	208	0
60-89 Days Past Due	0	0
Greater than 90 Days Past Due	0	0
Non-accrual Loans	0	0
Total Past Due	208	0
Loans Not Past Due	15,041	12,556
Total	15,249	12,556
Total [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	22,948	43,726
60-89 Days Past Due	6,635	8,680
Greater than 90 Days Past Due	499	630
Non-accrual Loans	99,861	103,902
Total Past Due	129,943	156,938
Loans Not Past Due	7,702,070	7,272,209
Total	$ 7,832,013	$ 7,429,147